Medical infusions are injected into bag-shaped containers, e.g., infusion bags and then are transported and stored.
Such a bag filled with a medical infusion contains nitrogen gas to prevent oxidation and degradation of the infusion. After a bag is filled with an infusion, the oxygen concentration of the infusion is measured to inspect whether the infusion is defective or not. In other words, it is naturally preferable that less oxygen is entrained during manufacturing, and thus when the oxygen concentration is higher than a permissible value, it is decided that the product is defective.
This inspection is conducted by a destructive method in which an injection needle is inserted into a product bag serving as a sample and air is collected to measure the oxygen concentration. After the inspection, the sample is discarded. Since the inspection is not a one hundred percent inspection but a sample inspection, safety and sanitation may not be secured.
For products in vial containers other than products in infusion bags, a method is available in which oxygen entrained or present in a container in the manufacturing process is detected by a laser beam (e.g., it is described in National Publication of International Patent Application No. 2007-508567 (hereinafter, will be referred to as Patent Literature 1)).
Specifically, in this method, a laser beam is transmitted to a gas phase portion on the top of a vial container and the amount of transmitted light is measured. In other words, the absorbance is detected to measure an oxygen concentration.
When an oxygen concentration in a bag is measured by a laser beam, it is necessary to keep constant the transmission distance of the laser beam (different distances naturally cause variations in measured oxygen concentrations).
As described in Patent Literature 1, a vial container is hard and thus a laser beam is transmitted at a constant distance, so that an oxygen concentration can be measured with relatively high accuracy.
However, infusion bags are made of soft materials and vary in thickness, so that non-destructive inspections using laser beams cannot be conducted with high accuracy.
In order to solve the problem, the applicant has proposed a non-destructive inspection device which can accurately inspect an oxygen concentration in a bag-shaped container filled with a liquid, by using a laser beam in a non-destructive inspection.
The non-destructive inspection device measures an oxygen concentration by emitting a laser beam to a gas phase portion while keeping bag shoulders in a horizontal position (For example, Japanese Patent Laid-Open No. 2010-38846(hereinafter, will be referred to as Patent Literature 2)).